From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.kernel.org ([198.145.29.99]:38458 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752989AbdHTOSW (ORCPT ); Sun, 20 Aug 2017 10:18:22 -0400 Date: Sun, 20 Aug 2017 15:18:18 +0100 From: Jonathan Cameron To: Linus Walleij Cc: =?UTF-8?B?TWljaGHFgiBNaXJvc8WCYXc=?= , Hartmut Knaack , Lars-Peter Clausen , Peter Meerwald-Stadler , "linux-iio@vger.kernel.org" Subject: Re: [PATCH 2/4] iio: magnetometer: ak8974: add_device_randomness(fw + serial) Message-ID: <20170820151818.7aa8f6e3@archlinux> In-Reply-To: References: <20170820112242.3008c3f8@archlinux> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-iio-owner@vger.kernel.org List-Id: linux-iio@vger.kernel.org On Sun, 20 Aug 2017 13:10:58 +0200 Linus Walleij wrote: > On Sun, Aug 20, 2017 at 12:22 PM, Jonathan Cameron wrote: > > On Thu, 17 Aug 2017 15:56:11 +0200 > > Michał Mirosław wrote: > >> Signed-off-by: Michał Mirosław > > > > Hmm. I wondered about the firmware version as a source of randomness, but > > will leave it in here. > (...) > >> + add_device_randomness(&fw, sizeof(fw)); > > > > The firmware version seems rather to guessable to really count as randomness. > > presumably it would constant for a particular batch of chips. > > That is true, this should go, not for security reasons but because it doesn't > add much device-unique randomness. Dropped the fw one... J > > Nothing we add with add_device_randomness() actually affects the entropy > pool trust, it is just icing making it - maybe - even more random, so adding > 256 zeroes is fine for the trust, just pointless and taking time for no good. > > Yours, > Linus Walleij > -- > To unsubscribe from this list: send the line "unsubscribe linux-iio" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html